1. Field of the Invention
The present invention relates to a novel human blue-light photoreceptor. More specifically, isolated nucleic acid molecules are provided encoding a human blue-light photoreceptor. Human blue-light photoreceptor polypeptides are also provided, as are vectors, host cells, antibodies, and recombinant methods for producing the same.
2. Related Art
In many organisms, the photolyase/photoreceptor family of proteins mediates DNA repair. In plants, certain developmental processes are regulated by blue-light. This regulation occurs by a photoinduced electron transfer reaction (Taylor, J. S., Acc. Chem. Res. 27:76-82 (1994); Menkens, A. E. et al., Biochemistry 34:6892-6899 (1995); Heelis, P. F. et al., Photochem. Photobiol. 95:89-98 (1996); and Sancar A., Science 272:48-49 (1996)). Indeed, to date, most of the work concerning blue-light photoreceptors has been conducted in plants (Cashmore, A. R. et al., International Patent Application WO 96/01897 (1996); Hinnemann, H., Photochem. Photobol. 61:22-31(1995); Short, T. W. et al., Annu. Rev. Plant. Physiol. Plant Mol. Biol. 45:143-171 (1994); Hohl, N. et al., Photochem. Photobiol. 55:239-245 (1992)) and fungi (Dunlap, J. C., Annu. Rev. Physiol. 55:683-728 (1993)). In plants, blue-light induces responses such as photomorphogenesis, phototropism and hypocotyl elongation. In particular, it has been demonstrated that the HY4 gene of A. thaliana, which encodes the CRY1 protein, is required for blue-light induced hypocotyl elongation (Ahmad, M., et al., Nature 366:162-166 (1993)).
In animals, most of the work on light response (other than vision) has been concentrated on circadian clocks. In D. melanogaster, two genes have been cloned, timeless and period, which regulate the circadian rhythm (Myers, M. P. et al., Science 270:805-808 (1995); Gekakis, N. et al., Science 270:811-814 (1995)). Both appear to be transcription factors for which activity is regulated by light. A mutation in the golden hamster tau gene disrupts the circadian clock (Ralph and Menaker, 1988). Three mouse genes, CLOCK, ICER, and CREM, which are involved in the control of circadian rhythm, have been investigated in some detail (Vitaterna et al., M. H. et al., Science 264:719-725 (1994); Sassone-Corsi, P. A., Rev. Cell Dev. Biol. 11:355-377 (1995); Foulkes, N. S. et al., Nature 381:83-85 (1996)). Each of these three gene products appears to be a transcriptional repressor for which activity is regulated by light. However, how the light signal is transmitted to these transcriptional regulators is not known.
Currently, the photolyase/photoreceptor protein family is known to contain three members: the cyclobutane pyrimidine dimer (Pyr<>Pyr) photolyase (photolyase), the (6-4) photolyase, and the blue-light photoreceptor (Todo, T. et al., Science 272:109-112 (1996)). The gene for the classical Pyr<>Pyr photolyase has been cloned and the enzyme has been purified from many organisms, including Escherichia coli, Saccharomyces cerevisiae, Drosophila melanogaster, and Carassius auratus (Sancar, A., Mutation Res. 236:147-160(1990); Kato, T. et al., Nucl. Acids Res. 22:4119-4124 (1994); and Yasui, A. et al., EMBO J. 13:6143-6151 (1994). The (6-4) photolyase has been found in D. melanogaster (Todo, T. et al., Nature 361:371-374 (1993); Kim, S. T. et al., J. Biol. Chem. 269:8535-8540 (1994)), Xenopus laevis, and Crotalus atrox (Kim, S. T. et al., Photochem. Photobiol. 63:292-295 (1996)).
Concerning the cloning of (6-4) photolyase genes, only the Drosophila gene has been cloned and sequenced (Todo, T. et al., Science 272:109-112 (1996)). The genes for the apoproteins of the blue-light photoreceptors of Arabidopsis thaliana (Ahmad, M., Nature 366:162-166 (1993)), Sinapis alba (Batschauer, A., Plant J. 4:705-709 (1993); Malhotra, K. et al., Biochemistry 34:6892-6899 (1995)), and Chlamydomonas reinhardtii (Small, G. D., et al., Plant Molec. Biol. 28:433-454 (1995)) have been cloned and sequenced. The photoreceptors of A. thaliana (Malhotra, K. et al., Biochemistry 34:6892-6899 (1995); Lin, C. et al., Science 269: 968-970 (1995)) and S. alba (Malhotra, K. et al., Biochemistry 34:6892-6899 (1995)) have been purified and characterized.
Circadian regulation of human and animal physiology, and particularly circadian regulation mediated by blue-light photoreceptors, is poorly understood. Thus, there is a need for an isolated human blue-light photoreceptor gene, the polypeptide encoded by that gene, and antibodies specific for that polypeptide.